In drilling and production applications where heat is applied, preserved, or recovered, thermal insulation design and efficiency impacts the efficiency of the process. Such applications include, for example, steam injection, arctic drilling, geothermal drilling, and the like. During such operations, wellbores typically are insulated to reduce heat transfer between the tubing, the casing, and the wellbore. Without effective insulation, heat from within the production tubing or transfer piping may thermally expand various components of the well. For example, expansion of the casing could damage the surrounding cement or break the bond between the casing and the cement. The well could collapse, fluid could leak from within the production tubing or transfer piping, and/or the casing could buckle or fail due to thermal stress.
Fluids comprising polymeric viscosifiers have potential for use in thermal insulation compositions. Unfortunately, polymeric viscosifiers tend to flocculate in the presence of temperature fluctuations over time. Eventually, flocculation of the polymeric viscosifiers tends to cause water separation and/or stratification, which renders the separated or stratified fluid less effective as a thermal insulation composition.
U.S. Patent Application 2004/0059054 apparently attempts to solve the foregoing problem using a thermal insulating packer fluid which comprises “at least one water superabsorbent polymer” which is said to be “capable in its dry state of absorbing and retaining a minimum of its own weight in water.”
Thermal insulation compositions which comprise polymeric viscosifier(s) and which remain homogeneous when exposed to water and temperature differentials over time are needed.